If you're like me, you run across a great needle sale and wonder if you already have that size! What's a knitter to do? Buy, just to find out when you get home, you already have 3 of this size? ARG! I carry a few of these cards in my purse just in case! You can check off the straight or circular ones you have already! I keep a separate one for the ones i DO need. I also keep one in my travel tin that holds all the essentials when I'm on the go! There are 10 cards on a page with all the information you need on one side, and plenty of room on the back to write down additional notes.